With the weight of the past on their minds, Gibbs and the team go back to work, with DiNozzo and McGee beginning a search for Ziva's replacement.
An investigation into the bizarre death of a Marine and two friends seems linked to Gibbs' past.
The team takes a second look into a lieutenant's death after the blogger who accused them of a cover-up turns up dead.
When a Marine's body surfaces halfway around the world, the investigation forces Ziva to dig up a lost chapter of her life.
A practical joke-loving Marine is found dead; Ziva adjusts to her new role on the team.
Two mercenaries are found dead on Gibbs' boat; Gibbs must consider his former mentor in a new light.
The team helps Vance face his demons while uncovering a complex relationship with a killer that endangers his family.
The team's investigation into a lieutenant's death is connected to a citywide blackout.
Thanksgiving plans are put on hold while the team investigates the horrific death of a Marine.
When the enlisted son of a preacher, who was a colonel, is found dead, the team thinks he may be the victim of a hate crime; Gibbs' father visits for the holidays.
When a Navy pilot is found dead in a secluded area, the team must battle a no-nonsense attorney with a hidden agenda.
Gibbs questions DiNozzo's ability to do his job when the elder DiNozzo gets involved in their latest investigation.
When an assassin targets the government's key witness in an embezzlement case, the team must help the witness make it home alive.
A terrorist group threatens to detonate a dirty bomb in Washington, D.C.
Fornell, Gibbs and the team try to bust an illegal trucking operation after a driver is found dead.
Secrets arise when Gibbs' former mother-in-law (Gena Rowlands) becomes a witness in a murder investigation.
While investigating a Marine's shooting, the team uncovers more to his life than anyone would have imagined.
The team and Coast Guard Investigative Services join forces when a Navy diver seeking sunken treasure is murdered.
The team turns to Holly Snow for help when a Navy officer's death is connected to a prostitute.
Gibbs, Fornell and the team try to determine the truth when a polygraph specialist's night job leads to murder.
DiNozzo gets overly involved in the search for a murder victim's missing sister.
An investigation into a Marine's murder leads to a surprising discovery; Abby and McGee head south of the border.
Gibbs makes shocking discoveries while investigating a respected colleague's murder.